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UNITED STATES NAVAL INSTITUTE, ANNAPOLIS, MD. 

June 7, 1886. 
Commander P. F. Harrington, U. S. N., in the Chair. 



CORROSION OF THE COPPER OF THE JUNIATA. 
By Charles E. Munroe. 



On October 23, 1882, 1 received telegraphic orders from the Secre- 
tary of the Navy to proceed to New York and examine the Juniata, 
with the object of ascertaining the cause of the corrosion of her 
copper. On reporting there I found the Juniata in dry dock, and 
an examination of her copper showed that the immersed surface had 
become covered with a pale green, earthy-looking coating, which at 
the time had become dry in spots and blistered. Many of these 
blisters had split, and the coating had flaked off to such an extent 
that the floor of the dock was thickly strewn with them. While the 
outer surfaces of these scales were of an apple-green color, the inner 
was, in the main, of a copper-red colorj though in some instances it 
was black. The surface of the copper where thus exposed was, in 
the main, of a copper-red color, but in some spots black. Where 
these black spots appeared they were imperfectly circular in shape. 

In addition to this general action which had caused the incrustation 
over the entire wetted surface, it was found that several plates had 
been so corroded as to be nearly or completely perforated. Eleven 
sheets on the keel, and sixteen on the bottom, most of them below 
the turn of the bilge, were so badly corroded as to require removal, 
and there were many others which gave promise of being soon in the 
same condition. This corrosion did not involve the whole of the 
plate on which it existed, nor was every plate attacked, nor in most 
cases contiguous plates, nor did it, in any case observed, extend to 
the nails or about them. The action was so irregularly distributed 
about the bottom and on the surface of the plates attacked, that there 






392 CORROSION OF THE COPPER OF THE JUNIATA. 

could be little doubt that the cause at work was a purely local one. 
When corrosion had gone on to the extent described, the outline of 
the spot was irregularly circular in shape, and the areas decreased 
unevenly from the outer surface inward, giving to the perforation an 
irregular cone-shape of very wide angle, the sides of the cone being 
in steps. The copper at these points seemed to be laminated. 

Further inspection showed that a portion of the copper on the keel, 
and all of the copper on the rudder, was covered with a greenish 
incrustation which was harder, firmer, and more coherent than that 
on the remainder of the ship, and that this copper was wholly free 
from any evidences of corrosion. The portion on the keel was mid- 
way fore and aft at the top of the keel. It was a goring-shaped 
section, and, roughly estimated, it was fifty feet in length, and tapered 
from eighteen inches wide midway to a point at either end. Although 
this strip was wholly free from local corrosion, yet sheets of copper 
below it, on the keel, and above it, on the hull, were corroded as 
described. So on the stern there were several corroded sheets, while 
the copper on the rudder, immediately adjacent, was free from all 
evidences of it. From their location it was evident that this copper 
on the rudder and the top of the keel had been subjected to the same 
conditions of exposure after immersion as the remainder of the copper 
on the immersed surface. 

The history of the Juniata was officially given as follows : When 
she had received her suit of copper, she was removed from the dry 
dock and lay in the Wallabout, under the iron derrick, for about five 
months ; she was then moved to the wharf at the foot of Main street, 
near Store No. 30, where she lay for one and a half months. From 
there she was moved to the ordnance dock, where she remained 
three days ; again moved to the foot of Main street, where she lay 
for a day and a half, and then was taken into the dry dock again. 
This was two days before I reported in New York. The corrosion 
noted had consequently taken place during the six to seven months 
in which the vessel was lying in the Wallabout. The copper on the 
rudder and the goring-shaped section on the keel were said to have 
been a portion of the old suit of copper which had been put on at 
the League Island Yard many years before. The goring-shaped 
piece owed its form to the fact that the ship was " hogged," and 
when pieces were inserted to straighten up the keel, it was thought 
unnecessary to strip the old copper from the old keel. 

My attention was next turned to the examination of the new, unused 



fttft 



/ 



'•3 09 



CORROSION OF THE COPPER OF THE JUNIATA. 393 

copper from which the copper for the Juniata had been taken. I 
first, while examining the bottom, inquired of the workmen if they 
had noticed any pecuharity in the appearance of the copper as they 
put it on, and I found that they had remarked upon the " picturing," 
as they termed it, which seemed to be unusual. I apphed then for 
sheets of copper from the same batch, and found that a few remained 
in the storehouse. On inspection I found that this " picturing " of 
which the workmen spoke was in the form of irregularly circular black 
spots and streaks on the surface of the copper. My first impression was 
that these spots were probably due to the fact that during transpor- 
tation moisture had gathered on the surface of the plates, and that 
this moisture had absorbed hydrogen or ammonium sulphide from 
the bilge gases of the ship in which they were transported, and that 
this had tarnished them ; but on examining the spots by light 
reflected at a wide angle, and by the sense of touch, it seemed prob- 
able that the plates had been rolled since the spots were formed, since 
the lustre on the spots was quite as brilliant as elsewhere on the sur- 
face. This theory of staining was not credited in the Constructor's 
Department of the Yard, as it was generally understood that the sheets 
were in this condition when put aboard the transport boat. 

I next directed my efforts to tracing up the history of the Juniata 
copper. I hoped to ascertain when it was received and where it was 
rolled ; then from the marks upon the sheets to learn from what batch 
of copper it had come ; then to follow up these cakes to the smelting 
works, and from this point determine the source and character of the 
ore from which it was made. With this knowledge of the source of 
the copper and the various processes through which it had passed, I 
hoped to discover the source of any physical or chemical imperfec- 
tions which the sheets might contain ; but at the outset I found that 
there were no marks upon these sheets of copper by which they could 
be identified, and that the different invoices received at the New York 
Yard were so mixed as to be indistinguishable. All that I could 
learn was that all of the sheathing used was rolled at the Washington 
Yard. Since such difficulties as have arisen in the case of the Juniata's 
copper are likely to recur, it will assist materially in discovering the 
source of the difficulty if the history of the copper is known. I would 
recommend that hereafter a full record of the copper should be kept, 
and that each sheet should be stamped in the upper left-hand corner 
with the number of the batch from which it comes. This mark will 
be preserved by the lap of the sheet above. That this is feasible is 



394 CORROSION OF THE COPPER OF THE JUNIATA. 

shown by a sheet of the old copper, stripped some two years previ- 
ously from the Brooklyn, after it had been some years in service, 
which bears distinctly the following mark in left-hand upper corner, 
•' U. S. N. Y. W., 1866." Starting from this point it will then be pos- 
sible to compile from the log-books of a ship such statistics regarding 
the time the copper has been in use, and the conditions to which it 
has been exposed, as will enable us to determine the average life of 
copper sheathing — an important fact about which there now seems to 
be considerable uncertainty. 

I next examined the Wallabout, a crescent-shaped body of water, 
something over 400 feet wide, lying between the Navy Yard proper 
and the cob dock. With the flood tide the current passes through 
to the westward, and with the ebb tide it moves to the eastward. 
Emptying into it are three sewers. At the east end, opposite the 
ordnance dock, is the Williamsburgh sewer, which drains 2300 acres of 
improved property, a considerable part being covered by petroleum 
refineries, chemical works, sugar refineries, and the like. About 500 
feet from the dry dock the Brooklyn sewer, which traverses the Navy 
Yard, empties into the Wallabout. This drains an area of about 550 
acres of improved property largely covered by residences. Near 
Store No. 30 a small sewer empties which drains a portion of the 
Navy Yard ; and near the west end of the Wallabout the Hudson- 
avenue sewer, which drains 472 acres of Brooklyn, empties. The 
result of all this sewage flowing into the Wallabout is to modify 
very considerably the character of the sea water. The first effect 
observed is that which always takes place where sewage, charged 
with dissolved and suspended matter, flows into salt water — viz. : the 
precipitation of the suspended and dissolved matter and the forma- 
tion of mud banks. This is going on continually in the Wallabout, 
and one of the largest banks was formed under the iron derrick 
where the Juniata lay for about five months. So shoal was it that 
she rested in the mud at low water, and in fact was probably im- 
bedded in it for the greater part of the time. From this bank I 
gathered specimens of the mud, and I also got specimens of the 
bottom from off" the ordnance dock. The first was regular dock mud, 
but the second consisted largely of coal tar. This last was accounted 
for by the existence, about opposite, of two large gas works, the 
" People's " and the " Nassau," while at the west end of the Wallabout 
there is a third. From the Williamsburgh and the Brooklyn sewers 
samples of sewage were taken. The color and character of the 



COlfROSION OF THE COPPER OF THE JUNIATA. 395 

sewage as it flowed from the sewers showed that the first was from 
factories, while the second was largely from dwellings. All the 
samples of sewage and mud were tested immediately after gathering, 
and all were found to be slighdy acid. Naturally the character of 
the sewage flowing in, and consequently of the water in the Wallabout, 
will vary with the season, the day, and "the state of the tide, so that 
the examination of only one set of samples is not of any value, 
except as indicating the character of the water at the time they were 
gathered. Realizing this, I applied to the Health Department of the 
city of Brooklyn, and also to Professor Charles F. Chandler, President 
Board of Health of New York, for information concerning the sewage 
emptying into the East River, but no investigation of this sort seems 
to have been made. Professor Chandler says, however, " There are a 
great number of petroleum refineries on Long Island at Hunter's 
Point and at Newtown Creek, and these refineries use enormous 
quantities of sulphuric acid, some portions of which find their way 
into the river. There are also chemical factories in Brooklyn — 
quite a number of them — and possibly their refuse materials are 
discharged from the sewers, by which the water along that shore may 
be rendered quite different from ordinary sea water." Through the 
courtesy of Civil Engineer F. C. Prindle, U. S. N., and Mr. J. H. 
Raymond, Commissioner of Health of the city of Brooklyn, I have 
obtained much of the information concerning the sewers which is 
given above. It would seem likely that considerable ammonia would 
reach the Wallabout from the gas works, were it not that ammonia has 
become so valuable an article, and the processes for recovering it from 
gas works have become so improved as to prevent much of it being 
allowed to escape. It is probable, too, that the considerable deposit 
of coal tar discovered at the end of the ordnance dock accumulated 
before these by-products of gas-making had become of any com- 
mercial value. 

Besides the specimens of mud and sewage, one sheet of new copper 
from the lot from which the Juniata's copper was probably taken, five 
corroded sheets stripped from the Juniata, a strip of the copper from 
the rudder of the Juniata, and a sheet of the old copper which had 
been stripped from the Brooklyn when she was last recoppered here, 
were taken for examination. 

Before leaving the Navy Yard I examined the pile of old copper 
stripped from the Brooklyn when she was last repaired. Although 
this had been in service many years (just how long I could not ascer- 



396 CORROSION OF THE COPPER OF THE JUNIATA. 

tain), much of it was so strong that it drew out the nails in coming 
off. Some of the sheets were eaten through in much the same way 
as was seen in the Juniata's copper, but there were very few of them. 
Naval Constructor W. L. Mintonye, U. S. N., informed me that 
sheets of this old copper had been used for covering the anchor hoy 
used in the Wallabout, that these sheets had been in use thus for about 
two years, and that during that time the anchor hoy frequently rested 
on the mud banks, yet the copper was sound. Mr. Mintonye also 
described some experiments which he had made with the Juniata's 
copper. He took sheets from the lot with which the Juniata was 
sheathed, and coupled them in pairs by blocks of wood. At the 
time the Juniata was coppered he buried one of these pairs in the 
mud ; the second was suspended six feet from the surface of the water, 
and the third was suspended at the surface of the water at low-water 
mark. These couples remained until the Juniata was docked in 
October, 1882. They were then taken out, and all were found 
unchanged except the couple buried in the mud, and these were 
only tarnished. 

During my inspection of the bottom of the Juniata, I was 
accompanied by Chief Constructor T. D. Wilson, U. S. N., and he 
suggested in explanation of the corrosion that it was due (i) to iron 
coming in contact with the copper, and that this probably occurred 
while the Juniata was lying in the mud bank under the iron derrick, 
as it was rumored that iron chains and other iron articles had been 
lost in this mud bank from time to time. Since my visit to the Navy 
Yard this mud bank has been removed by dredging, but I cannot 
learn that any such articles have been recovered. 

Another theory (2) advanced to account for the corrosion is that it 
was due to the sewage which flows into the Wallabout in such quantity. 
This was evidently in mind when my orders were drawn, as they 
read: ''Your attention is called to the fact that a large sewer 
discharges into the Wallabout at a point near the wharf to which the 
Juniata has recently been moved." 

Another (3) is that it was due to impurities in the copper, arising 
either from imperfect refining, impure ores, or the intentional admix- 
ture of foreign and cheaper metals. 

Another (4) is that it was due to iron removed by abrasion, or in 
the form of rust, from the rolls in the rolling mill. 

Another (5) is that it was caused by the adhesion of coal tar. 

Another (6) is that it was due to physical or chemical differences 



CORROSION OF THE COPPER OF THE JUNIATA. 397 

in different parts of the copper, which were caused by the method of 
manufacture. 

On the 6th of December, 1882, in obedience to orders I proceeded 
to Washington, and there examined the sheets of corroded copper 
from the U. S. S. Brooklyn which were sent from Rio Janeiro. The 
corroded sheets presented practically the same appearance as those 
from the Juniata. There was the same irregularly circular outline, 
and the corrosion was seen in all stages, from a roughened surface at 
the outer edge of the circle to a thin edge at the centre. Through 
the courtesy of the Chief of the Bureau of Construction, I examined 
the report of the condition of the Brooklyn, with the accom- 
panying drawings. These sketches showed that there was no regu- 
larity in the distribution of the corrosion, though most of the corroded 
sheets were below the turn of the bilge. 

On the 9th of December, in obedience to orders, I proceeded to 
New York to examine the U. S. S. Trenton, then in dry dock. On 
inspection I found her copper to be in a very sound condition, so far 
as local corrosion was concerned, the only corroded plates being six 
about each of the Kingston valves, one plate on the starboard side 
in contact with the stern being roughened, but not pierced, and one 
on the port side forward, just below and in contact with the ram. 
Besides these there were a few plates which had been indented and 
torn slightly, probably through colliding with some object. In 
addition I found that one sheet had been removed from the garboard 
strake on the port side, about 60 feet aft. I could not learn why this 
plate had been taken off. 

The history of this copper, so far as I could gather it, is as follows : 
The Trenton was in commission in Europe for some years, and on 
her return in October, 1881, she was laid up at the New York Yard. 
I am informed by her commanding officer. Captain F. M. Ramsay, 
U. S. N., that when she was brought in she was laid alongside the 
iron derrick, and she was so heavily loaded that it was with great 
difficulty that she could be forced into the mud bank under the 
derrick. After lying there some time she was drawn out into the 
Wallabout, and from that time until she was put into the dry dock in 
December, 1882, she lay nearly opposite the mouth of the Brooklyn 
sewer. The conditions, then, to which her old copper was subjected 
were almost identical with those to which the Juniata's new copper 
was subjected, the chief difference being that as the Trenton was 
heavily loaded, while the Juniata was light, the Trenton probably 
sank much deeper in the mud bank than the Juniata did. 



398 CORROSION OF THE COPPER OF THE JUNIATA. 

On December 20, 1882, in obedience to orders, I proceeded to 
Washington to inspect the rolHng mill at the Washington Navy 
Yard, then in operation. Here I witnessed the operations of hot 
rolHng and scaling, and my attention was particularly attracted to 
the latter process, as it did not seem to be complete, some portions 
of the scale being adherent after the removal from the bath, necessi- 
tating the cleaning of the sheet as completely as possible by mechani- 
cal means. As the treatment with the lye and acid was done in a 
very crude way, by rubbing on with a broom, this may account in a 
measure for the failure to entirely remove the scale or oxide. During 
my visit I was the recipient of courteous attentions from Commodore 
T. Pattison, U. S. N., commanding, and from Naval Constructor 
S. H. Pook, U. S. N., in charge of the rolling-mill, and the latter 
permitted me to take copies of letters, of recent date, from the 
managers of some of the principal rolling-mills in the country, from 
which I extract the following : 

Park, Scott & Co., Lake Superior Copper Mills, Pittsburgh, Pa., 
say : " The rolls in our mills which have given the most satisfaction 
are semi-steam-chilled." " We are not experienced as to what action 
sea water may have on sheathing made with iron rolls." 

C. G. Hussey & Co., Pittsburgh Copper and Brass Rolling Mills, 
Pa., state : " For rolling copper we use principally the chilled iron 
rolls, and as far as our experience has gone we find them well adapted 
for the work. We never knew of any iron from the rolls adhering 
to the copper, but black spots may be on the copper from imperfect 
removal of the scale or oxide. That is the only way we can account 
for black spots or marks." 

Hendricks Brothers, New York, write : " We consider chilled-iron 
rolls the best for the purpose referred to, and when replacing any at 
our own works, do so with those of that description. The rolling of 
copper in iron rollers is not detrimental for sheathing, nor would they 
injure it in any way as regards the action of sea water. The black 
spots spoken of are not iron, but copper scale or oxide, and do not 
affect the quality. Copper may be of equal purity, but some are 
harder than others ; the latter are preferred for the sheathing for ves- 
sels, on account of the action of salt water upon it." 

Pope & Cole, Baltimore, Md., write : ** The only suitable material 
for the construction of rolls for rolling copper is desl iron, chilled. The 
arrangements for rolling copper at the Washington Navy Yard are, 
in our judgment, so good that some time since we availed of permis- 



CORROSION OF THE COPPER OF THE JUNIATA. 399 

sion from headquarters to make copies of the working drawings in 
your mill, with the purpose of constructing one here, upon your 
method, in place of our present mill. The methods and surroundings 
of rolling copper have nothing whatever to do with the action of sea 
water upon copper sheathing on vessels. The trouble in cases where 
copper sheathing has become honeycombed or quickly worn thin 
when in contact with sea water is attributable to the fact of the pres- 
ence of a little silver in copper, which is quickly attacked by salt water. 
Copper for rolling can be procured which has no silver whatever in 
it — not a trace. The black specks or spots which you referred to 
are not iron : they are the oxide of copper. Copper and oxygen 
have a wonderful affinity for each other, especially when copper is hot 
or in a molten state. The oxide of copper, or, as known in commerce, 
'* copper scale," is easily removed from sheets by " pickling," and 
ought to be wholly removed before your sheets are cold-rolled. If 
you will heat a piece of bright polished copper and then expose it for 
one moment to the atmosphere, it will so quickly absorb oxygen 
therefrom as at once to become as black as iron." 

During this visit I received the following information from the 
executive officer of the Powhatan. " The Powhatan was lying at 
the wharf of the Brooklyn Navy Yard, near the iron derrick, from 
November 15, 1879, to January 23, 1880, and from December 23, 
1880, to March 24, 1881. Shortly after each of the above occasions of 
her stay off the Navy Yard she went into the dry dock, and upon 
examination the copper on the bottom of the vessel was found in per- 
fectly good condition." The conditions of exposure of the Powhatan 
evidently differed from those of the Juniata only in the fact that the 
latter was lying in the Wallabout during the summer months, while the 
former was there during the winter. This would to an extent prob- 
ably modify the action. 

On December 28, 1882, Commodore Pattison, U. S. N., sent me 
the following samples : Ingot copper, Pope & Cole ; ingot copper, 
Hendricks Bros. ; copper cake, Pope & Cole ; copper cake from 
refuse copper refined at the Washington Navy Yard. The ingot 
copper from Pope & Cole was full of air-holes ; the rest of the sam- 
ples were sound, fine-grained, and quite free from air-holes or cavi- 
ties, the specimen from the Washington Navy Yard being especially 
so. 

On December 12, 1882, I received the following letter: 



400 CORROSION OF THE COPPER OF THE JUNIATA. 

Bureau of Ordnance, Navy Department, 

Washington City, December ii, 1882. 
Professor Charles E. Munroe, Chemist, U. S. N. Academy. 

Sir: — In connection with the condition of the copper sheathing on the 
Brooklyn, I beg leave to say (as probably throwing some light on the subject) 
that the copper on the ferryboat Billow, at the Torpedo Station, put on in May 
last, is very badly pitted. 

This metal was furnished by the Bureau of Construction and Repairs, and 
the following analysis made* at the Torpedo Station shows that it contains 

foreign matters : 

Per Cent. 

Copper 98.492 

Lead 0.172 

Arsenic 0.290 

Nickel 0.102 

Cobalt 0.0 10 

Iron 0.570 

Oxygen 0.240 

Zinc 0.272 

100.148 
Also traces of silver and antimony. 

This copper may have been taken from the same lot from which the Brooklyn 
was coppered. The Bureau will be glad to make other analyses of copper, if 
desired. I am, sir, your obedient servant, 

Montgomery Sicard, 

Chief of Bureau. 

In reply to my inquiry as to the conditions to which the Billow had 
been subjected, Capt. T. O. Selfridge, U. S. N., commanding the 
Torpedo Station, states that " the Billow never has been aground 
since the copper was put on, and that she has only been exposed to 
the action of pure sea water." 

Learning that there had formerly been trouble from the water of 
Baltimore Harbor, I addressed a prominent shipbuilding firm there, 
and received the following reply : 

Baltimore, Md., December 14, 1882. 
C. E. Munroe, Professor, U, S. Naval Academy. 

Dear Sir: — Replying to your favor of 9th instant in reference to the cor- 
rosion of copper and metal on vessels' bottoms in Baltimore Harbor, we would 
state that previous to the stopping of the sugar refineries and the deepening of 
our harbor, all the steamboats whose landings were in the vicinity of the refinery 
or at the foot of the street where the sewage of the latter was discharged, 



By Professor J. Fleming White. 



CORROSION OF THE COPPER OF THE JUNIATA. 401 

suffered very much, and had to be docked for repairs or renewal of metal once 
each year, and in some cases at the refinery wharves twice in one year. The 
metal would be eaten worst at the water line around the nails in the seams of 
the plates. Some of the boats that used iron for protection against ice put it 
on in the fall and had to remove it in the spring, because it would be eaten 
away at the water line and interfere with the boats running. All these boats 
now run two, three and four years without docking, and, if they have pure 
copper on, we find it good after four years. We have some cases that we 
attribute to inferior metal. One we have just completed, the ship St. Albans, 
engaged in the Atlantic trade, metal been on twenty-six months, in active use 
eighteen months, honeycombed badly and had to be removed ; should have 
lasted forty months. Yours respectfully, etc., 

William E, Woodall & Co. 

In considering the case of the Juniata we must bear in mind that it 
is to be expected that copper sheathing will corrode in use, and that 
the peculiar advantage which it offers for keeping a ship's bottom 
clean is due to the fact that the copper is acted upon by sea water 
and forms a salt which, as it dissolves or scales, carries off the 
barnacles or seaweeds with it, and that this corrosion goes on over 
the whole immersed surface and continues throughout the whole 
period of immersion. 

What takes place with sound copper in pure sea water will occur 
in any solvent in which the copper is immersed. If there is no con- 
tact with other bodies, solid or gaseous, and no marked currents 
formed in the liquid, corrosion will take place equally over the whole 
surface of the copper, though the speed of the corrosion may differ 
with the solvents. 

What is peculiar about the corrosion of the Juniata's copper is that 
it was local and abnormally rapid. We will now take up the various 
theories proposed to account for this. 

I and 4. That it was due to contact with iron. 

On January 22, 1824, Sir Humphry Davy said : " The rapid 
decay of the copper sheathing of His Majesty's ships of war, and 
the uncertainty of the time of its duration, have long attracted the 
attention of those persons most concerned in the naval interests of 
the country. Having had my inquiries directed to this important 
object by the Commissioners of the Navy Board, and a Committee 
of the Royal Society having been appointed to consider of it, I 
entered into an experimental investigation of the causes of the action 
of sea water on copper. 

" It has been generally supposed that sea water had little or no 



402 CORROSION OF THE COPPER OF THE JUNIATA. 

action on pure copper, and that the rapid decay of the copper on 
certain ships was owing to its impurity. On trying, however, the 
action of sea water upon two specimens of copper sent by John 
Vivian, Esq., to Mr. Faraday for analysis, I found the specimen which 
appeared absolutely pure was acted upon even more rapidly than the 
specimen which contained alloy ; and on pursuing the inquiry with 
specimens of various kinds of copper which had been collected by 
the Navy Board and sent to the Royal Society, and some of which 
had been considered as remarkable for their durability, and others 
for their rapid decay, I found that they offered very inconsiderable 
differences only in their action upon sea water ; and, consequently, 
that the changes they had undergone must have depended upon 
other causes than the absolute quality of the metal. 

" When a piece of polished copper is suffered to remain in sea 
water, the first effects observed are a yellow tarnish upon the copper 
and a cloudiness in the water, which take place in two or three hours. 
The hue of the cloudiness is first white ; it gradually becomes green. 
In less than a day a bluish-green precipitate appears in the bottom of 
the vessel, which constantly accumulates, at the same time that the 
surface of the copper corrodes, appearing red in the water, and 
grass-green where it is in contact with air." 

Pursuing his experiments, Davy showed that there must be free 
oxygen present in water in order that copper might corrode, for 
"copper in sea water deprived of air by boiling or exhaustion, and 
exposed in an exhausted receiver or an atmosphere of hydrogen gas, 
underwent no change, and an absorption in atmospherical air was 
shown when copper and sea water were exposed to its agency in 
close vessels." 

From his investigations Davy ascertained that when copper, in 
contact with a metal which was electro- negative to it, was exposed to 
sea water, the electro-negative metal was attacked, and the copper 
was free from corrosion until the other metal was destroyed ; and he 
proposed to protect sheathing by this means. *' In pursuing these 
researches and applying them to every possible form and connection 
of sheet copper, the results were of the most satisfactory kind. A 
piece of zinc as large as a pea, or the point of a small iron nail, was 
found fully adequate to preserve forty or fifty square inches of copper, 
and this wherever it was placed, whether at top, bottom, or in the 
middle of the sheet of copper ; and whether the copper was straight, 
or bent, or made into coils. And where the connection between 



CORROSION OF THE COPPER OF THE JUNIATA. 403 

different pieces of copper was completed by wires, or thin filaments 
of the fortieth or fiftieth of an inch in diameter, the effect was 
the same : every side, every surface, every particle of copper remained 
bright, whilst the iron or the zinc was slowly corroded. 

" A piece of thick sheet copper containing on both sides about 
sixty square inches was cut in such a manner as to form seven 
divisions, connected only by the smallest filaments that could be left, 
and a mass of zinc of the fifth of an inch in diameter was soldered to 
the upper division. The whole was plunged under sea water ; the 
copper remained perfecdy polished. The same experiment was made 
with iron ; and now after the lapse of a month, in both instances, the 
copper is as bright as when it was first introduced, whilst similar 
pieces of copper undefended in the same sea water have undergone 
considerable corrosion, and produced a large quantity of green 
deposit in the bottom of the vessel. 

" A piece of iron nail about an inch long was fastened by a piece 
of copper wire nearly a foot long to amass of sheet copper containing 
about forty square inches, and the whole plunged below the surface 
of sea water ; it was found, after a week, that the copper defended 
the iron in the same manner as if it had been in immediate contact. 

" A piece of copper and a piece of zinc soldered together at one of 
their extremities were made to form an arc in two different vessels of 
sea water, and the two portions of water were connected together by 
a small mass of tow moistened in the same water; the effect of the 
preservation of the copper took place in the same manner as if they 
had been in the same vessel." {Phil. Trans. 1824, p. 151.) 

On p. 242 Phil. Trans. 1824 Davy gives a report of additional 
experiments on the protection of copper sheathing. He says : " Sheets 
of copper defended by from ^ to xTnjTr P^''^ ^^ their surface of zinc, 
malleable and cast iron have been exposed for many weeks in the 
flow of the tide in Portsmouth Harbor, and their weights ascertained 
before and after the experiment. When the metallic protector was 
from ^\j- to y-i-jy, there was no corrosion nor decay of the copper ; 
with smaller quantities, such as from -^-^ to y^, the copper under- 
went a loss of weight which was greater in proportion as the protector 
was smaller ; and, as a proof of the universality of the principle, it 
was found that even i-^-^-^ part of cast iron saved a certain proportion 
of the copper. 

" The sheeting of boats and ships protected by the contact of zinc, 
cast and malleable iron in different proportions, compared with that 



404 CORROSION OF THE COPPER OF THE JUNIATA. 

of similar boats and sides of ships unprotected, exhibited bright sur- 
faces, whilst the unprotected copper underwent rapid corrosion, 
becoming first red, then green, and losing a part of its substance in 
scales. 

*' Fortunately, in the course of these experiments it has been 
proved that cast iron, the substance which is cheapest and most easily 
procured, is likewise most fitted for the protection of copper. It 
lasts longer than malleable iron or zinc ; and the plumbaginous sub- 
stance which is left by the action of sea water upon it retains the 
original form of the iron, and does not impede the electrical action of 
the remaining metal." 

In Phil. Trans. 1825, p. 328, Davy gave the results of his 
" Further Researches on the Preservation of Metals by Electro- 
Chemical Means." He said : " As long as the whole surface of the 
copper changes or corrodes, no such adhesions (barnacles, etc.) can 
occur; but when this green rust has partially formed, the copper 
below is protected by it and there is an equal action produced, the 
electrical effect of the oxide, submuriate and carbonate of copper 
formed being to produce a more rapid corrosion of the parts still 
exposed to sea water ; so that sheets are often found perforated with 
holes in one part, after being used five or six years, and compara- 
tively sound in other parts. 

" There is nothing in the poisonous character of the metal which 
prevents these adhesions (barnacles, etc.). It is the solution by which 
they are prevented — the wear of the surface. Weeds and shell fish 
readily adhere to the poisonous salts of lead which form upon the 
lead protecting the fore part of the keel ; and to the copper, in any 
chemical combination in which it is insoluble. 

" In general, in ships in the Navy, the first effect of the adhesion of 
weeds is perceived upon the heads of the mixed metal nails, which 
consist of copper alloyed by a small quantity of tin. The oxides of 
tin and copper which form upon the head of the nail and in the space 
round it defend the metal from the action of sea water; and being 
negative with respect to it, a stronger corroding effect is produced in 
its immediate vicinity, so that the copper is often worn into deep, 
irregular cavities in these parts. 

" When copper is unequally worn, likewise in harbors or seas 
when the water is loaded with mud or mechanical deposits, this mud 
or these deposits rest in the rough parts or depressions in the copper, 
and in the parts where the different sheets join, and afford a soil or 



CORROSION OF THE COPPER OF THE JUNIATA. 405 

bed in which seaweeds can fix their roots, and to which zoophytes 
and shell fish can adhere. 

" As far as my experiments have gone, small quantities of other 
metals, such as iron, tin, zinc or arsenic in alloy in copper, have 
appeared to promote the formation of an insoluble compound on the 
surface, and consequently there is much reason to believe must be 
favorable to the adhesion of weeds and insects." 

Up to July, 1824, all Davy's experiments had been tried in harbor 
in comparatively still water, but soon after the protectors were tested 
on a steam vessel in the North Seas, and it was found that sheets of 
unprotected copper one foot square lost about 6.55 grains in passing 
at a rate of eight miles per hour in twelve hours ; but a sheet of the 
same size defended by rather less than -5^ lost 5.5 grains, and like 
sheets defended by ^ and y^ of malleable iron each lost 2 grains. 
These experiments show that there is a mechanical wear of the 
copper in sailing, and which, on the most exposed part of the ship 
and in the most rapid course, bears a relation of nearly 2 to 4.55. 
The copper sheets used weigh from 7000 to 8000 grains, and the bal- 
ance would detect a difference ofy^ of a grain in carrying this load. 

Further experiments showed that when air was excluded from a 
vessel containing sea water in which iron and copper or other cor- 
rodible metals were immersed, no action took place, and that the 
addition of an alkaline substance, even in presence of air, was suffi- 
cient to arrest corrosion ; but if the solution was strongly alkaline, then 
the electro-chemical action was reversed and the copper was corroded 
while the iron was preserved. The results of applying protecting 
masses of iron to coppered ships are cited, and the effect seems to have 
been advantageous ; but no instance is given where it had been tested 
for any long period. 

In closing he says : " The copper used for sheathing should be the 
purest that can be obtained; and in being applied to the ship, its 
surface should be preserved as smooth and equable as possible ; and 
the nails used for fastening should likewise be of pure copper ; and a 
little difference in their thickness and shape will easily compensate 
for their want of hardness." 

In the Comptes Rendus, 59, 15 ; 1864, M. Becquerel reviews 
Davy's work, and records the work which he himself carried on at 
Toulon under the direction of the Minister de la Marine, which con- 
firmed the views as to the protective action of iron on copper when 
immersed in sea water. 



406 CORROSION OF THE COPPER OF THE JUNIATA. 

In the Trans. InsL Nav. Arch. lO, i66; 1869, John Grantham, 
Benjamin Bell, Charles Lamport, John Scott Russell and C. F. J. 
Young, all testify to the destruction of iron in contact with copper, 
and the latter quotes Faraday, Wood, Normandy, Selwyn and 
Siemens in support of his views. These conditions, however, only 
hold true for sea water in an acid or neutral condition. At the time 
of my visit to the Wallabout I found the water and mud slightly 
acid, and if this be the prevailing condition of the Wallabout, it is 
impossible that the corrosion of the copper could have been due to 
the presence of iron. 

But while this relative action holds good for acid and neutral 
solutions in general, in most alkaline solutions, and especially solu- 
tions of the alkaline sulphides, the reverse is true, and the copper 
becomes electro-positive and is dissolved, while the iron remains un- 
acted upon. Davy pointed this out in 1812 {^Chemical Phil., p. 148), 
and again in 1825 (^Phil. Trans., p. 339) ; and Faraday, in his 
Experimental Researches in Electricity, Vol. II, p. 86, gives tables 
of the electro-chemical series for different solutions which show these 
facts. In order to test these statements I made experiments, taking 
solutions of ammonium carbonate and Severn- River water, and 
ammonium sulphide and Severn water. In each of these I inserted 
a strip of iron and one of copper in contact with each other and 
allowed them to stand. In 24 hours there was evidence of corrosion 
on the copper, and in one case where the action had gone on for two 
months the copper was eaten off to the surface of the liquid, and 
copper was deposited on the iron. The solution contained 10 cm. of 
yellow sulphide of ammonia of the ordinary strength to 200 cm. of 
water, and during the time spoken of the solution was in an open 
flask in a dimly-lighted hood. No quantitative experiments were made, 
since it was not important for this research in the case of the ammo- 
nium carbonate, and in the case of the ammonium sulphide the 
coating of sulphide on the copper made it difficult to determine the 
loss with any degree of accuracy. 

In determining if such a condition of circumstances could occur in 
the Wallabout, we may learn something from the examination of the 
sewage waters and mud. The sewage water taken at the mouths of 
the sewers was collected in patent-stoppered lager-beer bottles, which 
were carefully rinsed with the water to be collected. Although 
tolerably free from odor when collected, by the time they reached 
Annapolis they were highly charged with gases, which proved to be 



CORROSION OF THE COPPER OF THE JUNIATA. 407 

largely sulphide of hydrogen and some sulphide of ammonium. 
Through the decomposition they had become much more turbid 
from suspended matter than when first collected. So great was the 
pressure upon the bottles that, though they were kept in a cool 
place, one of them burst under the pressure of the confined gases. 
The sewage had become alkaline when it reached Annapolis. I 
give below the analyses of these waters, filtered, and of the sedi- 
mentary matter, and I add an analysis of the Severn-River water, 
since I used this in some of the experiments. The analyses given 
hereafter are usually the mean of several : 

Parts in 100,000. 
Solids. Ammonia. 

Vol. Non-vol. Total. Am. Al. Am. Salt. 

Williamsburgh 261.6 583.6 845.2 .1420 .1250 385.5 

Brooklyn 118.6 160.8 279.4 -0758 .0472 135.2 

Severn 157.0 1236.0 1393.0 io54-7 

SUSPENDED MATTER. 

Parts in 100,000. 
Vol. Non-vol. Total. 

Williamsburgh 31.2 84.0 114.2 

Brooklyn 22.6 38.1 50.7 

The result of such sewage as the above flowing into salt water must 
be, not only the production of mud banks, as stated above, but also 
the generation of hydrogen sulphide and alkaline sulphides, for the 
salt water contains calcium sulphate (in pure sea-water it will rise to 
100 parts in 100,000), and when organic matter comes in contact with 
this, calcium sulphide is formed, which gives off its sulphur as hydro- 
gen sulphide when it comes in contact with the carbon dioxide of the 
air. Ammonium sulphide will then be formed through reaction 
with the sewage. 

MUD. 

The mud was stored in new paint-kegs immediately after collect- 
ing, and on arrival here it was transferred to air-tight glass jars. 
When the mud from under the iron derrick was dried, it was of a 
bluish-white color and contained a considerable number of shells. It 
effervesced somewhat with acids, and when moistened it had a clay- 
like appearance. On drying, it gave off a slight offensive odor of 
animal matter. The mud from off the ordnance dock appeared, 
on drying, to be a mixture of blue mud with coal tar, and gave off the 



408 CORROSION OF THE COPPER OF THE JUNIATA. 

odor of coal tar on drying. The mud from the iron derrick lost 
15.23 per cent, of volatile matter on ignition, while the mud from the 
ordnance dock lost 24.51 per cent. When treated with ether, both 
yielded a yellow extractive matter, which on evaporation gave off an 
acrid odor. Both samples after exposure became alkaline. 

We see, then, that in the sewage emptying into the Wallabout we 
have materials for the formation of ammonium and other sulphides, 
and that, although at the time of my visit there the water was acid to 
neutral, yet, under the varying conditions prevailing, it is possible 
there are times when it may be alkaline. Is it, then, probable that iron 
in alkaline solution was the cause of corrosion ? I think not, and for 
the following reasons : 

If iron had fallen into this mud bank, it is probable that owing to its 
greater relative weight it would sink through the soft mud to the bot- 
tom. Now, there was considerable difference in height between the 
corroded plates highest up on the hull and those on the keel, and if 
the Juniata touched bottom on the keel, the iron in contact with the 
higher plates must have been buoyed up. Since, however, there 
was room for the much heavier Trenton to get in, it is probable 
that the Juniata did not touch hard bottom. This argument may, 
however, be met by supposing that both the vessels lay on the flat 
of the bilge in a trough in the bottom of the Bay. 

Another consideration is that the corrosion is too local for simple 
contact. None of the holes were over two inches in diameter, nor 
the roughened spaces about them more than eight inches. Now, cop- 
per is a good conductor, and with sheets as thick as these it seems 
strange that the action should be confined to so small an area. I do 
not lay much stress on this point. 

What seems to me conclusive is that both the Powhatan and the 
Trenton lay in the same berth without injury, and that the copper on 
the rudder of the Juniata and the goring-piece on the keel were under 
precisely the same conditions as the remainder of the copper on the 
Juniata, and they were not corroded ; and finally, that the copper 
on the Billow was corroded in a similar way without having been 
exposed to like surroundings. 

2. That it was due to sewage. Since household sewage may 
contain sodium carbonate and hyposulphite from the soap used, and 
zinc chloride and bleaching powder from the disinfectants employed, 
I tested the action of these substances upon both copper and oxide 
of copper, the substances and the solutions being enclosed in stoppered 
bottles. The following are the results after seven months' action : 



CORROSION OF THE COPPER OF THE JUNIATA. 409 

Copper and sodium hyposulphite — copper coated with sulphide — 
no copper in solution. 

Copper oxide and sodium hyposulphite — no copper in solution. 

Copper and sodium carbonate — copper coated with green carbonate 
— considerable copper in solution. 

Copper oxide and sodium carbonate — faint trace of copper in solu- 
tion — the copper oxide unchanged in appearance. 

Copper and zinc chloride— deep green deposit of copper chloride 
on sides of bottle — copper bright. 

Copper oxide and zinc chloride — no action. 

Copper and bleaching powder — copper coated with bluish coat — 
copper in solution. 

Copper oxide and bleaching powder — trace of copper in solution. 

All of these substances act upon the copper, but the last two would 
be destroyed by the organic matter in the Wallabout, and the first 
two would probably not exist any length of time in their original 
condition. But granted that any of them were present and free to 
act, or that there were free acids or ammonia or ammoniacal salts 
present, could they produce such corrosion as took place on the 
Juniata ? In my opinion not, because they would be dissolved in the 
water or in a layer at the surface, and would produce corrosion over 
the entire immersed portion of the copper or else at the water line, 
while that of the Juniata was purely local and confined to widely and 
irregularly separated spots. 

3. That it was due to impurities in the copper arising from 
imperfect refining, impure ores, or the intentional admixture of foreign 
and cheaper metals. 

In the paper by Davy quoted above, it will be seen that the 
presence of iron, tin, zinc, arsenic and the like, in small quantities, 
promoted the formation of insoluble scale on copper. In Pope and 
Cole's letter we see that they attribute corrosion to the presence 
of silver. This view was advanced by A. A. Hayes (y^w. Jour. Sci. 
[2] II, 324). He says : " Some analyses I made, many years since, of 
sheathing copper which had long resisted the action of sea water 
proved the presence of one ten-thousandth part of silver. It was 
found that even this small portion of silver sensibly modified the 
chemical relations of the metals, and observations had indicated that 
the quality for sheathing was improved. Copper of this kind is 
frequently met with in commerce, and is derived from the Chilian 
ores of copper, which, although argentiferous, do not yield enough 
silver to render its separation economical. 



4IO CORROSION OF THE COPPER OF THE JUNIATA. 

" An occasion offered for again examining this subject, when the 
argentiferous native copper of Lake Superior was first refined and 
rolled by the Revere Copper Co., more than five years since, and the 
results have lately been obtained. Four suits of sheathing, for large 
merchant vessels, formed the subjects for observations, the metal 
being of uniform composition, as determined by assay of the clipping 
from many sheets. Two thousand parts of the alloy contained four 
parts of pure silver, or the standard ton of this country contained four 
pounds of silver (0.20 per cent.). 

'' K proximate analysis of this metal was also made, and it proved 
to be pure copper throughout, the mass of which, an alloy of silver 
and copper, was evenly distributed so as to form either a mixture or 
a compound alloy, in which one part of the copper is truly combined 
with the silver, and the other and larger part simply combines with 
the alloy. This is a very common constitution of alloys, in which 
two metals exist without any metalloid occurring to disturb the 
simplicity of the union, and always indicates a careful purification of 
the metals. 

" It was assumed as probable that the silver alloy would close the 
pores of the copper, which takes place with a tin alloy in bronze, and, 
in a mechanical way, confers durability. If, however, corrosion should 
take place, it was in accordance with observed cases that the silver 
alloy would act as a negative element, and the copper alone would be 
removed. How erroneous these inferences proved will be seen in the 
detail of the results. 

"The Chicora was coppered January 9, 1847, taking 7392 pounds 
of metal, which was fastened by bronze nails. She was employed in 
trade to China, and wore her copper so rapidly that it was removed 
in March, 1849, 2628 pounds only remaining. In this case the 
sheets, after the usual operations, had been consolidated by 'cold- 
rolling.' 

"The Serampore was coppered January 18, 1847, requiring 8447 
pounds of * cold-rolled ' metal, secured by bronze nails. She sailed 
to China and home via Cape of Good Hope, and to the Pacific and 
home via Cape Horn, requiring new copper in March, 1850. The 
weight of the remaining copper was not ascertained. 

"The Hamilton was coppered October 22, 1847, requiring 7706 
pounds metal, secured by bronze nails. The sheets used were in the 
ordinary or annealed state. This vessel was employed in the India 
trade, and wore out her copper in August, 1849. The weight of the 
copper remaining was 3086 pounds. 



CORROSION OF THE COPPER OF THE JUNIATA. 411 

** The Carthage was coppered November 26, 1847, requiring 8727 
pounds 'cold-rolled' metal, fastened by bronze nails. She was 
employed in the India trade, and her sheathing was destroyed in 
August, 1849. The copper remaining weighed 5810 pounds. 

"Omitting the case of the Serampore, where the corrosion cannot 
be determined by weight, we have the loss in every one hundred 
parts of metal, for the time of duration, thus : The Chicora, twenty- 
seven months, lost 64.45 per 100 ; the Hamilton, twenty-three months, 
lost 59.95 per 100 ; the Carthage, twenty-one months, lost 33.45 per 
100. 

" Allowing the same rate of corrosion, and taking the time as 
twenty-seven months for each : The Chicora lost 64.45 in 100 ; 
the Hamilton lost 70.38 in 100; the Carthage lost 43.00 in 100. 

" In the cases of the Hamilton and Carthage we perceive the 
influence of the different processes of manufacturing the sheets on 
the durability of the copper. By the operation of ' cold-rolling ' the 
surfaces of the sheets are rendered very compact, and in any cor- 
roding solution they bear a negative relation to the metal in the 
same sheets between these surfaces. Such copper is also always 
strongly negative to annealed copper in acid solutions until the 
hardened surfaces are removed; it then loses this relation. The 
Hamilton exhibits the greatest effect of sea-water action on the 
annealed alloy, while in the Carthage the protecting influence of the 
hardening surface was exerted nearly to the time her copper was 
removed. These observations establish the fact of the rapid cor- 
rosion of an alloy thus constituted, and show its entire unfitness for 
sheathing purposes. 

"The average duration of copper sheathing decreases slightly as 
the requirement of greater speed in sailing is more urgent. Taking 
one hundred merchant ships, sailing on different oceans, the average 
duration now on American ships is three years. 

" On the point of the kind of corrosion following the exposure of 
the alloy to sea water and air, the information obtained of these 
trials is of a definite character. Part of the sheets remaining, and 
an ingot of the copper from smelting a large quantity, were assayed, 
and the results showed that the same proportion only of silver 
remained as was originally contained in the alloy. The silver, there- 
fore, by taking the negative state in the mass of the metal alloy has- 
tened its destruction, while its own form and condition were such 
that it separated as the copper was corroded." 



412 



CORROSION OF THE COPPER OF THE JUNIATA. 



In this connection I made the following analyses. In these analyses 
I designate the copper from the rudder of the Juniata as " rudder 
copper," that taken from the Juniata after corrosion as " old Juniata 
copper," that taken off from the Brooklyn, in order to put on her 
present suit, as " Brooklyn copper," and the new sheet from the New 
York storehouse as " new Juniata copper." 

In the analyses of the coppers, I have followed the methods given 
by Andrew A. Blair, chemist to the United States Board for Testing 
Metals, which appear as an appendix to Ex. Doc. 98 of the Forty- 
fifth Congress, Second Session ; and I have also employed the method 
of W. Hampe, given in Zeitschrift filr Analytische Chemie, 176, 
1874, and in Watts' Dictionary of Chemistry^ Vol. VIII, Part I. 
The methods have sometimes been modified in a measure, to accom- 
modate them to the appliances at hand. In the table, the "rudder 
copper " is No. i ; the " Brooklyn," No. 2 ; the "new Juniata," No. 3, 
and the " old Juniata," No. 4. The results given are the mean of a 
number of determinations : 





I. 


2. 


3- 


4. 


Copper, 


99.428 


99.225 


98.426 


98.509 per cent. 


Silver, 


.125 


.085 


.005 


.010 


Arsenic, 


trace. 


none. 


•135 


•159 


Antimony, 


none. 


none. 


.008 


.005 


Lead, 


.010 


.080 


.178 


•152 


Iron, 


.183 


.252 


.650 


.580 


Nickel, 


none. 


none. 


.050 


.010 


Zinc, 


none. 


none. 


.170 


.150 


Bismuth, 


.005 


.003 


.012 


.015 


Oxygen, 


•155 


.185 


.280 


•235 



99.906 



99.830 



99.914 



99.825 



For comparison with these, I have sought to obtain analyses of 
different American coppers from the principal sources, in order that 
we might determine what would be termed " pure copper " in com- 
merce here, but I have been unable, as yet, to obtain such, so I give 
(i) an analysis of a "refined copper," from Oker, made by Hampe, 
and reported in Fresenius' QuantHativen Chemischen Analyse^ 
2, 527; 1882 ; (2) an analysis of a " refined copper " from Colorado, 
made by T. Egleston, Ph. D., and given in Trans, of American 
Institute of Mi?iing Engineers for October, 1882 ; (3) an analysis of 
" ingot Lake Superior copper," Andrew A. Blair, loc. cit. 295. 



CORROSION OF THE COPPER OF THE JUNIATA. 



413 





I. 


2. 


3. 


Copper, 


99-325 


99.705 


99.420 per cent, 


Silver, 


0.072 


0.135 


0.014 


Gold, 


0.0001 


... 


... 


Arsenic, 


0.130 


0.091 


none. 


Antimony, 


0.095 


... 


none. 


Bismuth, 


0.052 


... 


none. 


Lead, 


0.061 


none. 


trace. 


♦Iron, 


0.063 


0.031 


0.013 


Cobalt, 


0.012 


... 


... 


Nickel, 


0.064 


... 


... 


Sulphur, 


0.00 1 


trace. 


... 


Oxygen, 


0.1166 


... 


... 


Tellurium, 


... 


0.083 


' 


Zinc and nickel. 


... 


G.024 


... 


Suboxide of copper, . . . 


... 


0.537 


Carbon, 


... 


... 


0.041 



99.9917 



100.069 



100.025 



The Juniata copper, then, is not so pure as the rudder copper or 
the Brooklyn copper, or the copper last cited. The excess of silver in 
the rudder and Brooklyn coppers may at first excite remark, but we 
must remember that both of these coppers had been exposed to sea 
water for a very long time, and that sea water contains chloride of 
silver in solution, and that silver will be deposited upon copper under 
these circumstances. Mulder, in his Die Silber-Probirmethode, 27, 
states that chloride of silver is soluble in solutions of all the metallic 
chlorides which are soluble in water. Watts' Dictionary of Chem- 
isi^y^St 271, states that silver has been detected in sea water, and 
refers to Ann. Ch. Phys. [3] 27, 129, which I have not been able to 
consult, and T. Sterry Hunt, Chem. and Geol. Essc^s, 231, repeats 
this statement. To test it, I placed some freshly precipitated and 



*In examining the copper for iron, I deemed it important to test the nitric 
acid used, although it was bought, as chemically pure, through Desaga, of 
E. Merck, of Darmstadt. The first bottle examined was but partially full, and 
had been standing for some time in strong sunlight, and was evolving nitrous 
fumes, notwithstanding that the glass was of a dark greea color. Analysis 
showed it to contain .00135 gram of iron in 100 cm. Another full bottle of the 
same lot, which had been standing in the dark, was tested, and was found to be 
free from iron. This last was used in the analyses. 



414 



CORROSION OF THE COPPER OF THE JUNIATA. 



washed chloride of silver in Severn water and inserted a strip of copper. 
In twenty-four hours a decided coating of silver was deposited on the 
copper. 

The amount of silver present in the Juniata coppers seems, how- 
ever, too small to have been the source of this trouble, and of the 
other substances found, the oxygen appears the one most likely to 
have been the cause of the trouble. It should be said that the darker, 
spotted portions of the new sheets were taken for analysis, and that 
on especially removing the surface from some of these spots by the 
aid of a bright steel file-scraper, I found it to consist of a film of oxide 
free from sulphide. But as from the first my attention and that of 
others had been called to this unusual feature in the copper, and as 
these spots closely resembled the corroded spots in form, it seemed 
proper to select these portions. I am not, however, assured that the 
oxide originally existed in the copper. 

The following experiments were made to ascertain if corrosion 
would take place between copper and copper oxide in the presence of 
the materials in the Wallabout. Heavy, cold-drawn copper wire 
was cut into pieces. Each piece was then bent, and one end was 
heated in the flame until it was coated with oxide. The strips were 
then immersed in the solutions or buried in the mud, as given in the 
table below. We then had an electro-chemical couple with copper 
and oxide of copper. In the experiments cited below, No. 5 and 
No. 6 were the most satisfactory as regards the cleanliness of the 
copper after removal from the solution and washing : 

Substance Used. Loss. Remarks. 

1. Copper and Williamsburgh sewage. 1.42 per cent Liquid alkaline — con- 

tained coal tar. 

2. Copper oxidized and Williamsburgh Liquid alkaline — con- 

sewage 1.45 " tained coal tar — 

copper pitted. 

3. Copper and Brooklyn sewage 3.42 " Liquid faintly alkaline. 

4. Copper oxidized and Brooklyn Liquid faintly alkaline 

sewage 2.99 *' — copper pitted. 

5. Copper and mud from under shears Liquid faintly alkaline 

and Severn water 7.24 " — no pitting. 

6. Copper oxidized and mud from Liquid faintly alka- 

under shears and Severn water... 14.64 " line — copper badly 

pitted. 

7. Copper and mud from Ordnance Liquid alkaline — no 

Dock and Severn water 4.06 •' pitting. 

8. Copper oxidized and mud from Ord- Liquid alkaline — cop- 

nance Dock and Severn water.... 3.06 •* per faintly pitted. 



CORROSION OF THE COPPER OF THE JUNIATA. 415 

As in these cases the solutions were all slightly alkaline, I repeated 
the experiments with Severn-River water, and with common-salt 
solutions, and in each case the copper was corroded. In addition, I 
connected my couple with a galvanometer»and got a marked deflec- 
tion of the needle. Hence there can be no doubt that electro- 
chemical action can go on between copper and copper oxide in 
sea water. This view is supported by the fact that all authorities 
are agreed that the corrosion of pure copper by pure sea water 
cannot take place in the absence of air. This air supplies oxygen, 
and the first step in the process of corrosion is one of oxidation. If, 
then, the copper be oxidized when immersed, the process is facilitated. 

5. That it was caused by the adhesion of coal tar. In the examina- 
tion of the Juniata, no coal tar was observed in contact with the cor- 
roded spots, though small amounts were noticed elsewhere, the 
copper at those points being sound. In the experiments last cited, 
when coal tar was present it adhered to the copper so firmly that it 
was difficult to remove it, and it formed a strongly adherent varnish 
or lacquer which seemed to protect the copper from corrosion. 

6. That it is due to physical or chemical differences in different 
parts of the copper which were caused by the method of manufacture. 
From the consideration of all the circumstances, and especially of the 
facts that the copper is found to be spotted with oxide ; that these 
spots are irregularly distributed over the plates ; that they generally 
agree in configuration and size with the corroded spots, and that the 
copper at the corroded spots appears laminated, I am led to conclude 
that this theory is the more probable one, and that the imperfections 
result from blister-holes in the copper and the incomplete removal 
of the scale. 

We have found that in the existence of these spots of scale or 
oxide we have a condition which is favorable to the commencement 
of the corrosion. Why does it continue ? 

If we examine one of the corroded spots from which the surface 
has been removed, we find that the remaining surface is roughened. 
Now, such a surface is more readily attacked than a polished surface. 
This latter is a well-known fact in connection with the " rusting " or 
corrosion of metals, and it is for this reason largely that metal articles 
are polished. But it seems to me that there is an additional reason 
for action at this point. In the Proc. Nav. hist. 8, 502 I have shown 
that annealed steel is much more soluble in sea water than " tempered " 
or hardened steel, and that when in contact the soft metal is rapidly 



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416 CORROSION OF THE COPPER OF THE JUNIATA. 

corroded. I have recently been confirmed in the truth of my obser- 
vations by the investigation of M. Gruner in Comptes RenduSy 96, 
195. I am inclined to the opinion that the same holds true of copper 
of varying hardness, and- 1 find support for my opinion in the state- 
ment of A. A. Hayes.''' I believe that the copper beneath the spots of 
scale is softer than that about it, and furnishes the differences neces- 
sary for this action. 

My theory to account for the existence of these differences and for 
the formation of the spots is as follows : I assume that an unsound 
cake of copper is taken for rolling which contains cavities like those 
seen in the ingot from Pope & Cole. When this is rolled into a bar, 
the cavities will be extended in the direction of the length of the bar. 
When the pieces of bar are afterwards rolled into sheets, these cavi- 
ties will also be extended in the direction of the width of the sheet. 
These changes in form would of course be irregular, and would tend 
to produce such shapes as were seen on the copper. These cavities 
would necessarily contain gas, and copper is a very excellent con- 
ductor of heat, while gases are as a rule very poor conductors. Then, 
when the whole is heated and allowed to cool, the space about the 
cavity would be longer in cooling than the remainder, and, as a con- 
sequence, more scale would be formed at that point than elsewhere, 
and might adhere more firmly, or its formation might continue after 
the scaling process was considered complete. This layer of oxide 
and cushion of gas would then prevent the copper at this point from 
becoming as hard, through rolling, as over the remainder of the sur- 
face. The fact that the copper appears slightly laminated at some of 
the corroded spots seems to substantiate this theory. It may be 
objected that an enclosed gas at the high temperature of the operation 
would exert pressure sufficient to burst the envelope, but we must 
remember that the cavities were formed when the gas was at the 
temperature of molten copper. 

In conclusion, I would state that in my opinion the corrosion of 
the Juniata's copper was due principally to the presence of spots of 
oxide of copper on the surface of the plates at the time they were 
put on, and I would recommend in the future the use of a pure copper, 
care in the production of sound cakes, and careful removal of the 
scale. 

* Loc. cit. 



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